Tapachula, Mexico is immediately adjacent to a malaria area where there has been recent spraying with DDT, and women from the malaria area deliver their children in Tapachula hospitals. We have a study in Tapachula which went into the field in July 2001. The first goal is to verify that the blood levels of DDE are significantly elevated among a portion of women giving birth in Tapachula. If enough levels are high, then a small study of DDE and anogential distance will go forward. We want to see whether the androgen-blocking effect of DDE observed in animals?reduced anogenital distance?is also seen in humans. Once this small study is underway and I have evidence of a successful field effort, I will make arrangements to revise and expand the study to address the question regarding DDE in relation to preterm birth. Peer review of the revised protocol will be obtained. If DDE levels are not as high as anticipated (unlikely), then the contract will be recompeted, with the goal of finding a more highly exposed study population to test the hypotheses. Aims: 1) To examine the relation between maternal serum levels of the androgenic DDT metabolite DDE in relation to anogenital distance in 200 male newborns in Tapachula, Mexico, where there has been recent, high-level exposure to DDT, 2) To conduct a pilot study of the relation of maternal DDE levels to risk of preterm birth (n=75 cases, 150 controls). The study went into the field in July 2001.. Pilot data have confirmed the high exposure levels and the feasibility of measuring anogenital distance in Mexico.